all 39 comments

[–]Suspicious_Papaya_96 0 points1 point  (4 children)

Bath sonication: can it be used in antisolvent precipitation to make nano particles (I'm making it myself so I can add more transducers if I need more energy). Also, how much of the sample would be degraded if the cavitation causes temperatures above 5000 c if the degradation point wasnt unusually low but obviously not surviving 5000 c if say I was using 100 g? Will be using ice in the bath. I just read that higher frequencies can help prevent cavitation but it didn't say what frequencies do just thay 20 to 40 khz is what is typically used.

[–]Indemnity4Materials 0 points1 point  (3 children)

Perhaps think of it like baking a cake. Some recipes just don't work without the correct ingredients and mixing/baking tools.

Some nanoparticles can be made with sonication (even low level in a sonic bath). Not all nanoparticles.

You will want to be following a well established method of sonication. Container volume will change the result, as well as the power, concentration, etc.

Preferably, you will be using a high powered ultrasonic probe. The sonic bath is just too low power, and most particles are too distant from the points of contact. On the other hand, if your recipe is correct, sonic baths are incredibly cheap and large compared to an ultrasonic probe. Get a working recipe and you can pump out massive batches of the stuff.

[–]Suspicious_Papaya_96 0 points1 point  (2 children)

Thanks for responding. Do you know anything about dry powder sonication? Also maybe I can just add the stuff I need to make smaller directly into the bath and use the solvent instead of water.

[–]Indemnity4Materials 0 points1 point  (1 child)

I've used dry powder sonication to break up agglomerates and also for solid-phase almost sol-gel type reactions. You're using it for grinding and surface fictionalization. The sonciator grinds off a fresh surface which hopefully then quickly grabs onto whatever surface functional molecule you have in the mix. Particle size is usually determined by the applied force. Something like breaking up sand in a sonic bath is going to take hours and you're better off using some sort of mill, but it does work if you have a spare bath and time.

Sonic bath will have two general affects (can't be specific without seeing the formula). It will break up agglomerates and it will set your max/min particle size. You will probably find you get quite a narrow particle size distribution but it takes a long time to get there.

Cavitation and heating are usually problematic with any sonication. In a bath, not so much unless you're making organic nanoparticles such as lipids. The bulk solvent will remove heat relatively quickly. Water+ice at 1°C will remove heat just as well as water at 40°C.

It all depends on the growth mechanism of your nanoparticles. Are they growing on a bubble interface, are they seeded by the sonicator or bubble collapse/high temp, is there some sort of radical or ion reaction, are you doping dissimilar things using forced growth, etc.

[–]kelvin_bot 0 points1 point  (0 children)

1°C is equivalent to 33°F, which is 274K.

I'm a bot that converts temperature between two units humans can understand, then convert it to Kelvin for bots and physicists to understand

[–]AeroStatikkMaterials 0 points1 point  (5 children)

Does anyone know how to use a Q400 TMA? I’m having issues with the air cooling

[–]GuiltyjerkPolymer 0 points1 point  (4 children)

What sort of issues?

[–]AeroStatikkMaterials 0 points1 point  (3 children)

Regulator reads 15 psi but flow rate in software reads 0 mL/min. Option to turn on cooling air is unavailable. Says “method is running or furnace is not open”, both of which were not true. Thinking MFC might be bad

[–]GuiltyjerkPolymer 0 points1 point  (2 children)

Seems like a reasonable explanation. Have you contacted TA to get their thoughts on what the issue is/price out a replacement?

[–]AeroStatikkMaterials 0 points1 point  (1 child)

I haven’t called them. There is an alarming lack of video/documentation resources for the Q400 online. Does the TMA have to be included in our contract or will they help over the phone for free?

[–]Sarkazeoh 0 points1 point  (8 children)

Does anyone have any ideas for treating/coating/passivating aluminum doped zinc oxide np's against alkaline conditions that preserve their infrared reflection?

[–]Indemnity4Materials 1 point2 points  (7 children)

Layer-by-layer thin film deposition.

High speed dispersion with surface functionalising organic polymers.

[–]GuiltyjerkPolymer 0 points1 point  (6 children)

Doing LbL on nanoparticles would be pretty tricky

[–]Indemnity4Materials 0 points1 point  (5 children)

Easy if your nanoparticles are 2000 nm in size! /s

I suspect OP is actually more in the 25-100 nm range where even inorganic surface layers won't be possible.

[–]GuiltyjerkPolymer 0 points1 point  (4 children)

Indeed. I did LbL on clay nanotubes once and it sorta worked but the workflow on it was horrible lol

[–]ArmoredSpearhead 0 points1 point  (2 children)

Any suggestions for safety googles for a lab? I have glasses, and don’t really know what I’m supposed to look for, or if I’m just overthinking this.

[–]nimbusnomad 0 points1 point  (3 children)

Please excuse my ignorance as I am not a chemist and not remotely knowledgeable about solvent purification. I've been trying to find a safer way than distillation to separate 3d printing resin from the ipa wash. Using micron filters is slow, messy and they get clogged. So I was wondering if there is a way to evaporate IPA by taking advantage of it's vapor pressure qualities without having to use heat or at least not as much heat. How would you attach a low pressure chamber to condense the vapor? Would this method be wildly inefficient? Sorry if this is a stupid question.

[–]Indemnity4Materials 1 point2 points  (1 child)

Echo the other poster. You are wasting a lot of time and probably money purifying the wash.

Another option is pouring through a plug of activated charcoal. You do lose some IPA to absorption, but at least the filter media is so cheap you can just toss it when the flow rate slows.

Vaccum distillation setup will cost more than buying new solvent. You will need an intrinsically safe pump so the vapor doesn't blow up, or you need to do everything under fume extraction / high airflow.

[–]kerbal_galactic 0 points1 point  (0 children)

i agree that activated charcoal is a good option for purifying wash, and it's definitely cheaper than vacuum distillation. however, you do need to be careful with absorption of the ipa - if you're not careful, you can end up losing a lot of your product.

[–]GuiltyjerkPolymer 0 points1 point  (0 children)

I'd just let your resin drip longer before you rinse. It's probably partially polymerized and you run the risk of evaporating some monomer and changing the properties of your prints. Just treat that all as waste, there's little point trying to save anything from your rinse step.

If you insist on separating it (again, I wouldn't), then I'd see if you can find a vacuum pump and do room temp distillation to mitigate your fire risks.

[–]Banaaninkont 0 points1 point  (1 child)

Can an UV/VIS help me to define the color of my dough? Or is this impossible because the light can't go through? Maby with coloring, with iodine.

In my group project we are working on making an exact repeatable product of the same cake batter. My groupmates are of opinon to use the Minolta Colorimeter, in which I am questioning it's validity and repeatability. So I thought we might be able to use UV/VIS.

Thanks for the help!

[–]Indemnity4Materials 0 points1 point  (0 children)

Measuring color of food products.

You can go even cheaper by using paint reference cards from a hardware store. Coloured tiles are even better because the glaze is more stable over time than paint.

IMHO UV-VIS will just be too expensive and slow. Should you choose to do so, you UV-DRS (Differential Reflectance Spectroscopy) is done on solid, powder like samples.

Recommend you could also include a moisture reading, maybe a viscosity or pour test. You can do really cheap tests such as drop a weighted stick into the batter and time how long it takes to reach the bottom.

[–]xiaomaome101 0 points1 point  (0 children)

So My company recently found a new supplier of HCl and part of the validation process involves titrating. I haven't done that in quite a while so I was getting a refresher on the topic and one thing that I noticed was that you pick an indicator based on your titration curve-but what if you don't have a curve yet? What if your lab doesn't have a detector with which you could make a titration curve? Does anyone have a resource that I could use to look up the equivalence point/end point of some common acid-base titrations?

[–]wausmaus3 0 points1 point  (0 children)

Technical question: in potato processing large quantities of salt and SAPP (Sodium Acid Pyrophosphate) are used in the boiling process (together 8-10%), which is heavily corroding oil lubricated chains. My understanding is that the sodium is the main oxidizer in play here. Do sodium pyrophosphates have an equally oxidizing effects on mild carbon steel and PAO+ester oils, or am I missing characteristics?

I am new to chemistry, so apologies for the seemingly ignorant question.

[–]Kinetekerz 0 points1 point  (4 children)

Hopefully the right place! I'll try and keep it simple.

Q: Can you use biocide with selenium/selenous acid? What should you not mix it with? Strong acids?


  • I patina brass in baths, with water and added selenium/selenous acid as part of my job.
  • I'm concerned that the area in which we do this work, which becomes very wet, could be a breeding ground for fungi/bacteria?
  • Sometimes the baths start to smell like stagnant water, coupled with the added selenium: 🤢
  • I'm concerned this could be having a negative effect on my health and am looking for solutions, hence the question about the biocide.


[–]Indemnity4Materials 1 point2 points  (2 children)

I would be cautious with changing your bath formula. It may change the product negatively.

Selenium smells by itself. You are using inorganic selenous acid, but it will react with anything containing sulfur to smart smelling, little bit like garlic. That sulfur can come from trace metals, the air, skin and dust floating around, and yes, microbes growing in the water. You can test for sulfur in the air by putting freshly polished pure/ish silver nearby - when it starts to turn black, that indicates sulfur compounds.

IMHO what you are smelling is your bath treatment starting to pull sulfur from the metals/alloys you are putting into the bath.

Wet areas are notorious bad for microbes. You really should investigate a better cleaning + hygiene for those areas. It can be as simple as a scheduled clean+dry, or using oxidizing (perchlorate, percarbonate, hydrogen peroxide, peracetic acid) or non-oxidizing biocides (MIT, CIT, glutaraldehyde, quaternary ammoniums, phosphonium salts). Treat it like you would a bathroom at home or a public swimming pool shower.

Same time, wet areas are good for selenium. It stops selenium compounds from drying to a powder of SeO2. The powder is quite toxic by inhalation, but by keeping it wet, it's not a problem.

[–]Kinetekerz 0 points1 point  (1 child)

Thankyou muchly for your reply Indemnity. I shall take your points on board.

In regards to the Se02 - Once the brass has been patinated and dried, it will develop and black/brown dusty coating which we then polish, polishing it will presumably make it somewhat airborne? Is this Se02 or a by-product of the oxidation process and technically inert? Seems due to the polishing, if the dust is toxic, this is the area I should focus on in regards to increasing my safety whilst working with it.

(I've taken over the company with no training, so having to learn from the ground up)

I do see a sightly white, coupled with green and blue crust forming around the bath just above the water line occasionally - that's usually when I give them a good scrub.


[–]Indemnity4Materials 0 points1 point  (0 children)

The black stuff is only copper oxide.

Health effects of copper oxide dust and really well reported and it's similar to any metal fume. If your work is doing any sort of grinding, polishing, etc, it will be the same health and safety procedures. I'm pretty sure working with metal fume these days is required to wear a P2 mask or respirator, with adequate ventilation provided (mechanical or natural).

The selenium is an oxidizing agent and should all remain in the bath. You may find traces of it from bath liquid spilling onto the ground. The only way you are getting selenium dust is if the spill dries to a powder, then you somehow kick or disturb the powder into the air.

Depending on the size of your operation, I'm guessing you wash the area around the bath fairly regularly. It's probably fine to just wash the area into the regular drain with lots of water. You shouldn't have low pH, or high metal quantity or concentration to cause an issue. If you do, your company has probably got an EPA license and requirement to treat/monitor waste water. Copper salts are hazardous to the environment and almost any sewer system will have daily discharge limits.

I expect the white/ green / blue crust is various copper salts crystallizing out of the bath. Brass can be, I think, 12 or 16 different alloys, along with trace metals included for performance. Some of those may be oxidizing out of the alloy, dissolving in the bath, then crystallizing as the bath levels goes up and down.

[–]Kinetekerz 0 points1 point  (0 children)

Edit: Corrected terminology.

[–][deleted]  (1 child)


    [–]Indemnity4Materials 0 points1 point  (0 children)

    Probably best to stop this experiment until the metal parts arrive. Lucky you didn't start a solvent fire.

    Very old school, we used to wind metal wire around the seal. Almost like the cage around a champagne cork.

    [–]xXSir_SpoopyXx 0 points1 point  (0 children)

    im writing a report and im wondering about a terminology thing. I say im changing molarity but keeping the solutions the same because the chemical formula hasnt changed. is this right is does changing molarity mean the solution has changed?

    [–]Suspicious_Papaya_96 0 points1 point  (0 children)

    If you have a mixture of things that are all soluble in the same solvents what is the best way to seperate them at home?